The de t’ part just sounds like de with a t sound on the end, followed by ça, as if it were deutt ça.

It was a woman in her 60s who said de t’ça, but it can be heard in any age group during informal conversations.

You don’t need to start saying de t’ça yourself. Just learn to recognise it. The regular de ça pronunciation works in any language situation, for example: je suis tanné de ça, or more informally: chu tanné de ça.

If you are going to use de t’ça though, keep it for informal language situations.

By the way, the woman really did say je suis, and not the informal contracted forms j’sus (chu) or j’suis (chui).